Image source: Flickr user Steve Jurvetson.

What: After reporting positive mid-stage trial results for its migraine therapy, shares in Alder Biopharmaceuticals (NASDAQ:ALDR) are soaring 55.06% higher at 12:00 p.m. ET.

So what: The clinical stage company reported earlier today that its ALD-403 for the treatment of the prevention of migraine met its primary endpoint.

The study evaluated ALD-403 to determine if it could more effectively reduce the occurrence of migraine versus placebo. Five treatment arms, including four of varying dose and the placebo arm, were evaluated, and it was found that 31% and 33% of patients taking the 100 mg and 300 mg dose experienced a 75% reduction in migraine days over 12 weeks. 21% of patients in the placebo group saw a similar 75% reduction.

Now what: This is big news for the company and migraine sufferers.

ALD-403 is the most advanced drug in Alder Biopharmaceuticals' pipeline, and the positive study results suggest the company could eventually have a top seller on its hands. Roughly 13 million patients in the U.S. could benefit from a migraine prevention therapy such as ALD-403, including 3 million people who suffer from chronic migraine.

The company plans to meet with the FDA to discuss its findings, and management has already begun enrollment in one phase 3 study of ALD-403. A second phase 3 study of the drug is expected to begin later this year.

Obviously, anything can -- and often does -- derail clinical-stage drugs in late-stage studies, so investors should still view this company as a risky bet, but this news does add confidence, and that's something that's been in short supply in biotech this year. 

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.